A Multifrequency Collimation Profile Analysis of the 3C279 Jet

Relativistic jets emanating from supermassive black holes at the center of active galactic nuclei (AGN) are some of the brightest objects in the universe. Despite their status as one of the most energetic phenomena, the process by which these plasma jets are released and the structure of this collimation is still unknown both observationally and theoretically. While lower-luminosity AGN (LLAGN) such as M87 have well-studied collimation profiles, the structure of more powerful quasar jets is much less understood due to the proportionally greater distances that quasars are typically observed at.

Here, we present a multifrequency analysis of the archetypal quasar 3C279 in the sub-milliarcsecond to milliarcsecond scales, using data taken by VLBA, GMVA including ALMA, and global VLBI observations over a frequency range of 22 - 86 GHz.

The higher angular resolution provided by both the global VLBI array and GMVA including ALMA allowed for better resolution of jet structure, revealing a parabolic shape to the sub-milliarcsecond scale of the jet. This suggests that the jet collimation occurs on the scales of ~2×10⁵ - 4×10⁶ Schwarzchild radii (R_s) from the central engine, in contrast to M87, where collimation occurs up to ~10⁵ R_s , while jet width is consistent across both sources. These conditions imply the presence of dense, confining material existing at quasar’s nuclei on much larger scales than LLAGN, which generally exert a sphere of gravitational influence of radius 10⁵ R_s

This work was supported by grants (AST-1440254, AST-1614868, AST-1950348, AST-2034306) from the National Science Foundation, and grants (PID2019-108995GB- C21, P18-FR-1769, SEV-2017-0709) from the government of Spain.